Study On Influence Of Admixture On Fiber-reinforced Cement-based Composite

Fiber-reinforced cement-based composite have attracted more and more attention in both material and engineering fields. Traditional asbestos cement-based composite materials have been replaced gradually by non-asbestos-cement products because lack of asbestos reserves and its harm to human health.In this paper, polypropylene fiber and wood fiber was used to improve the mechanical properties especially the bending strength. The composition and preparation process of fiber-reinforced cement-based composite materials was studied systematically. On the basis of previous experiments, the effect of additive on mechanical properties of composite materials was investigated in detail.Using the rapid hardening sulphoaluminate cement as the main gel material, the silica powder, calcium carbonate powder, swelling perlite as the aggregate, the wood fiber, wood powder, polypropylene fibers as the strengthen fiber, the FDN, lignin sodium as the quality of water reducer, the fly ash and gypsum as the additive, fiber-reinforced cement-based composite materials was prepared through compression molding methods.The orthogonal experiments identified optimum percentage of wood fiber, perlite, and polypropylene fiber, which is 7.5g, 10g, and 7.5g per 100g of gel respectively. Under the best conservation condition of normal temperature and high humidity, further experiments are carried out to determine the optimum percentage of additives and water reducer. It is identified that the optimized ration is 80:20:5 for cement, fly ash, and gypsum respectively; and the quantity of FDN and the lignin sodium per 100g of gel is 0.6g and 0.15g respectively. Materials of different water-cement ratio are also examined for the mechanical properties, and therefore determined the optimal water-cement ratio is 0.3375. The mechanical behavior of composite materials under bending load is tested and the micro-structure on surface section is analysis by scanning electron microscopy. This helps to explain the mechanical behavior and the impact of additives on mechanical performance of composite materials. In all, optimum gradient percentage is achieved and the performance of composite materials is improved for experimental purposes comprehensively.